Radio Frequency Identification (RFID) technology is becoming widely used in virtually every industry, including transportation, shipping, manufacturing, postal tracking, consumer goods, food, medical practice, airline baggage reconciliation, and highway toll management.
A typical RFID system includes a plurality of RFID tags or labels, at least one RFID reader or detection system having an antenna for communication with the RFID tags or labels, and a computing device to control the RFID reader. An RFID tag typically does not include a layer of adhesive. An RFID label typically is an RFID tag having a layer of adhesive for attaching the RFID tag to an item. RFID tags typically include an integrated circuit and an antenna, the combination of which are often referred commonly in the industry as an “RFID inlay.” The RFID reader includes a transmitter that may provide energy or information to the tags or labels, and a receiver to receive identity and other information from the tags or labels. The computing device can process the information obtained by the RFID reader.
In general, the information received from an RFID tag or label is specific to the particular application, but often provides an identification for an article to which the tag is affixed. Exemplary articles include manufactured items, shipping containers, books, files, industrial, medical or forensic samples, animals, or virtually any other tangible article. Additional information may also be provided for the article. The tag or label may be used during a manufacturing process, for example, to indicate a paint color of an automobile chassis during manufacturing or other useful information.
The transmitter of the RFID reader outputs RF signals through the antenna to create an electromagnetic field that enables the tags or labels to return an RF signal carrying the information. The transmitter makes use of an amplifier to drive the antenna with a modulated output signal.
A conventional RFID tag or label may be an “active” tag or label that includes an internal power source, or a “passive” tag or label that is energized by the field created by the RFID reader antenna. Once energized, the tags and labels communicate using a pre-defined protocol, allowing the RFID reader to receive information from one or more tags or labels. The computing device serves as an information management system by receiving the information from the RFID reader and performing some action, such as updating a database. In addition, the computing device may serve as a mechanism for programming data into the tags or label via the transmitter
A typical RFID system includes RFID tags or labels that are affixed to objects and an RFID reader that can read and optionally write unique identification information stored on the tag or label and provides generally automated, error-free identification of the objects. Often it is desirable to affix the RFID tag or label to the object permanently or at least for the duration of time that the object will be used and identified or for the lifetime of the object, so that errors due to removing the tag from the correct object and reattaching that tag to an incorrect object are generally eliminated. Additionally, it saves time and effort if RFID tags do not have to be removed and reattached to objects during the lifetime of the objects. Thus, it is desirable that the RFID tag or label remain functional (for example, able to receive and send information) for the time and under the various conditions that the object will be used and identified. Various situations or conditions during the lifetime of the RFID tag or label on the object may cause the RFID tag or label to become non-functional.
It is advantageous to use RFID tags and labels to identify a number of objects that will be exposed to microwave radiation during their lifetime of use. For example, RFID labels might be used to identify medical specimens, manufacturing samples, forensic samples or other laboratory samples that are processed with the aid of microwave energy in laboratory equipment. As another example, an RFID label might be used to identify a food product that will be heated in a home-use microwave oven. Japanese Patent Office Publications 2005-242629A and 2004-138331 disclose wireless integrated circuit (IC) tags on food container and cooking utensils for use in cooking appliances, such as microwave ovens. U.S. Pat. Nos. 7,031,946 and 6,892,545 disclose the use of RFID tags on food items that could go into a microwave oven. As another example, RFID tags or labels might be used to identify electronics components or devices or optical components or devices that are processed in manufacturing with microwave radiation. For example, curable materials may be cured in manufacturing with the aid of microwave radiation.